KR102744330B1 - Surface-treated infrared absorbing microparticles, surface-treated infrared absorbing microparticle powder, infrared absorbing microparticle dispersion using the surface-treated infrared absorbing microparticles, infrared absorbing microparticle dispersion, and infrared absorbing substrate - Google Patents

Abstract

The present invention provides surface-treated infrared absorbing fine particles, wherein the surface of the infrared absorbing fine particles is covered with a coating film including at least one selected from a hydrolysis product of a metal chelate compound, a polymer of a hydrolysis product of a metal chelate compound, a hydrolysis product of a metal cyclic oligomer compound, and a polymer of a hydrolysis product of a metal cyclic oligomer compound, and the infrared absorbing fine particles have a crystallite diameter of 30 nm or more.

Description

Surface-treated infrared absorbing microparticles, surface-treated infrared absorbing microparticle powder, infrared absorbing microparticle dispersion using the surface-treated infrared absorbing microparticles, infrared absorbing microparticle dispersion, and infrared absorbing substrate

The present invention relates to surface-treated infrared-absorbing fine particles, which are infrared-absorbing fine particles that transmit light in the visible range and absorb light in the infrared range, and whose surfaces are covered with a predetermined coating film; surface-treated infrared-absorbing fine particle powder containing the surface-treated infrared-absorbing fine particles; an infrared-absorbing fine particle dispersion using the surface-treated infrared-absorbing fine particles; an infrared-absorbing fine particle dispersion; an infrared-absorbing substrate; and a method for producing them.

In recent years, the demand for infrared absorbers has been rapidly increasing, and many patents regarding infrared absorbers have been proposed. When considering these proposals from a functional standpoint, for example, in the fields of window materials for various buildings or vehicles, there are those that aim to sufficiently receive visible light while blocking near-infrared light, thereby maintaining brightness and suppressing temperature rise in the room, and those that aim to prevent infrared rays radiating forward from a PDP (plasma display panel) from causing malfunctions in remote controls for cordless phones or home appliances, or from having adverse effects on optical transmission systems.

In addition, from the viewpoint of a light-shielding member, for example, a light-shielding member used in window materials, etc., has been proposed, which includes a light-shielding film containing a black pigment including an inorganic pigment such as carbon black or titanium black having absorption characteristics from the visible light range to the near-infrared range, and an organic pigment such as aniline black having strong absorption characteristics only in the visible light range, and a half-mirror type light-shielding member deposited with a metal such as aluminum.

For example, in Patent Document 1, a composite tungsten oxide film containing at least one metal ion selected from the group consisting of groups IIIa, IVa, Vb, VIb, and VIIb of the periodic table is provided as a first layer from the substrate side on a transparent glass substrate, a transparent dielectric film is provided as a second layer on the first layer, and a composite tungsten oxide film containing at least one metal ion selected from the group consisting of groups IIIa, IVa, Vb, VIb, and VIIb of the periodic table is provided as a third layer on the second layer, and further, the refractive index of the transparent dielectric film of the second layer is made lower than the refractive indices of the composite tungsten oxide films of the first layer and the third layer, thereby suggesting an infrared-blocking glass that can be suitably used in a portion where high visible light transmittance and good infrared-blocking performance are required.

In addition, in Patent Document 2, an infrared-blocking glass is proposed in the same manner as in Patent Document 1, in which a first dielectric film is formed as a first layer from the substrate side on a transparent glass substrate, a tungsten oxide film is formed as a second layer on the first layer, and a second dielectric film is formed as a third layer on the second layer.

In addition, in Patent Document 3, a heat-shielding glass is proposed in which, in the same manner as in Patent Document 1, a composite tungsten oxide film containing a metal element similar to that in Patent Document 1 is formed as a first layer from the substrate side on a transparent substrate, and a transparent dielectric film is formed as a second layer on the first layer.

In addition, Patent Document 4 proposes a solar control glass sheet having solar shielding properties, which is formed by thermally decomposing at about 250°C a metal oxide film selected from one or more of tungsten trioxide (WO ₃ ), molybdenum trioxide (MoO ₃ ), niobium pentoxide (Nb ₂ O ₅ ), tantalum pentoxide (Ta ₂ O ₅ ), vanadium pentoxide (V ₂ O ₅ ), and vanadium dioxide (VO ₂ ), which contains an additive element such as hydrogen, lithium, sodium, or potassium, by a CVD method or a spray method.

In addition, Patent Document 5 proposes a solar variable dimming insulating material which uses tungsten oxide obtained by hydrolyzing tungstic acid and adds an organic polymer having a specific structure called polyvinylpyrrolidone to the tungsten oxide. When the solar variable dimming insulating material is irradiated with sunlight, ultraviolet rays in the light are absorbed by tungsten oxide, and excited electrons and holes are generated, and a small amount of ultraviolet rays significantly increases the amount of pentavalent tungsten appearing, so that the coloring reaction becomes faster, and the coloring density increases accordingly. On the other hand, by blocking light, pentavalent tungsten is very quickly oxidized to hexavalent, so that the decolorization reaction becomes faster. By using the coloring/decolorization characteristics, it is proposed to obtain a solar variable dimming insulating material which has fast coloring and decolorization reactions to sunlight, has an absorption peak at a wavelength of 1250 nm in the near-infrared range during coloring, and can block near-infrared rays of sunlight.

Meanwhile, the inventors of the present invention disclosed in Patent Document 6 a method of obtaining a tungsten oxide fine particle powder containing tungsten trioxide or a hydrate thereof or a mixture of the two by dissolving tungsten hexachloride in alcohol, evaporating the medium as it is or heating and refluxing, evaporating the medium, and then heating at 100° C. to 500° C. Then, they disclosed that an electrochromic element is obtained using the tungsten oxide fine particles, that a multilayer laminate is formed, and that when protons are introduced into the film, the optical properties of the film can be changed, etc.

In addition, Patent Document 7 proposes a method for producing various tungsten bronzes expressed as MxWO 3 (M; a metal element such as an alkali, alkaline earth, or rare earth, 0 < x < 1) by using meta-type ammonium tungstate and various water-soluble metal salts as raw materials, heating a dried product of a mixed aqueous solution thereof at a heating temperature of about ₃₀₀ to 700°C, and supplying hydrogen gas to which an inert gas (amount added; about 50 vol% or more) or water vapor (amount added; about 15 vol% or less) has been added during the heating. In addition, a method for producing various tungsten bronze-coated composites by performing the same operation on a support is proposed, and use thereof as an electrode catalyst material for fuel cells and the like is proposed.

And, the inventors of the present invention disclosed in Patent Document 8 an infrared shielding material particle dispersion in which infrared shielding material particles are dispersed in a medium, excellent optical properties, conductivity, and a manufacturing method of the infrared shielding material particle dispersion. Among these, the infrared shielding properties were superior to those of conventional shielding materials. The infrared shielding material particles are particles of tungsten oxide represented by the general formula WyOz (wherein W is tungsten, O is oxygen, 2.2≤z/y≤2.999) or/and composite particles represented by the general formula MxWyOz (wherein M is at least one element selected from H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, I, W is tungsten, O is oxygen, 0.001≤x/y≤1, 2.2≤z/y≤3.0). It is a fine particle of tungsten oxide, and the particle diameter of the infrared shielding material fine particle is 1 nm or more and 800 nm or less.

Japanese Patent Publication No. 8-59300 Japanese Patent Publication No. 8-12378 Japanese Patent Publication No. 8-283044 Japanese Patent Publication No. 2000-119045 Japanese Patent Publication No. 9-127559 Japanese Patent Publication No. 2003-121884 Japanese Patent Publication No. 8-73223 International Publication No. 2005/37932 International Publication No. 2010/55570

According to the review of the present inventors, in the optical member (film, resin sheet, etc.) including the above-mentioned tungsten oxide fine particles and/or composite tungsten oxide fine particles, it was found that, depending on the usage situation or method, water vapor or water in the air gradually penetrates into the solid resin included in the optical member. In addition, it was found that when water vapor or water gradually penetrates into the solid resin, the surface of the above-mentioned tungsten oxide fine particles decomposes, the transmittance of light having a wavelength of 200 to 2600 nm increases over time, and the problem that the infrared absorption performance of the optical member gradually deteriorates was found. The solid resin is a polymer medium that is solid at room temperature, and also includes a polymer medium other than a three-dimensionally cross-linked one (in the present invention, it is sometimes described as a "matrix resin").

In addition, according to the review by the present inventors, in the tungsten oxide fine particles or composite tungsten oxide fine particles disclosed in Patent Document 8, it was found that the surface of the fine particles undergoes oxidation deterioration due to heat exposure, and further, the infrared absorption effect is lost. In addition, it was found that active harmful radicals are generated in a polymer medium such as a solid resin due to heat exposure, and also the surface of the fine particles undergoes decomposition deterioration due to the harmful radicals, and further, the infrared absorption effect is lost.

Under the circumstances described above, the inventors of the present invention disclosed in Patent Document 9 an infrared-shielding particle having excellent water resistance and also excellent infrared-shielding properties, which is a tungsten oxide particle represented by the general formula WyOz and/or a composite tungsten oxide particle represented by the general formula MxWyOz, wherein the average primary particle size of the particle is 1 nm or more and 800 nm or less, and the surface of the particle is coated with a tetrafunctional silane compound or a partial hydrolysis product thereof, and/or an organometallic compound, and a method for producing the same.

However, infrared absorbing materials are basically used outdoors due to their characteristics, and in many cases, high weather resistance is required. And as the demand in the market increases year by year, further improvement in water resistance and moisture resistance is also required for the infrared shielding particles disclosed in Patent Document 9. In addition, the infrared shielding particles disclosed in Patent Document 9 lack the effect of improving resistance to heat exposure, that is, heat resistance, and thus, certain issues remain.

In addition, infrared shielding particles have often been applied to high visible light transparency infrared shielding particle dispersions that require high visibility by taking advantage of their optical characteristic of selectively shielding infrared rays. As a result, infrared absorbing materials such as the infrared shielding particle dispersion have also been required to have a low haze value (sometimes referred to as “low haze” in the present invention).

The present invention has been made under the circumstances described above, and its object is to provide surface-treated infrared-absorbing fine particles having excellent moisture-heat resistance and heat resistance and also excellent infrared absorption characteristics, a surface-treated infrared-absorbing fine particle powder containing the surface-treated infrared-absorbing fine particles, and an infrared-absorbing fine particle dispersion using the surface-treated infrared-absorbing fine particles, and further to provide a low-haze infrared-absorbing fine particle dispersion and an infrared-absorbing substrate having excellent infrared absorption characteristics and high moisture-heat resistance, heat resistance, and visible light transparency.

In order to solve the above-described problem, the present inventors conducted research on a configuration that makes it possible to use the tungsten oxide fine particles or/and composite tungsten oxide fine particles having excellent optical properties as infrared absorbing fine particles and to improve the moisture-heat resistance and chemical stability of the infrared absorbing fine particles. As a result, they found that it was urgent to cover the surface of each infrared absorbing fine particle using a compound that has excellent affinity with the surface of the infrared absorbing fine particle and is further uniformly adsorbed to the surface of each infrared absorbing fine particle to form a strong coating film.

The present inventors continued their research and found that a metal chelate compound or a metal cyclic oligomer compound is a compound having excellent affinity for the above-described infrared absorbing fine particles and forming a coating film. As a result of further research, they found that a hydrolysis product of these compounds, or a polymer of the hydrolysis product, which is generated when the metal chelate compound or the metal cyclic oligomer compound is hydrolyzed, is a compound that uniformly adsorbs to the surface of each infrared absorbing fine particle and also forms a strong coating film.

That is, the surface of the tungsten oxide fine particles or/and the composite tungsten oxide fine particles is covered with a coating film including at least one selected from a hydrolysis product of a metal chelate compound, a polymer of a hydrolysis product of a metal chelate compound, a hydrolysis product of a metal cyclic oligomer compound, and a polymer of a hydrolysis product of a metal cyclic oligomer compound (in the present invention, it is sometimes described as "surface-treated infrared-absorbing fine particles"). In addition, it was found that the surface-treated infrared-absorbing fine particles have excellent heat and moisture resistance.

In addition, it was found that the surface-treated infrared-absorbing fine particles, the surface-treated infrared-absorbing fine particle powder containing the surface-treated infrared-absorbing fine particles, the infrared-absorbing fine particle dispersion manufactured using the infrared-absorbing fine particle dispersion liquid in which the surface-treated infrared-absorbing fine particles are dispersed in a suitable medium, etc., have excellent moisture-heat resistance and also excellent infrared absorption characteristics.

The inventors of the present invention continued their research and discovered that when the crystallite diameter of the infrared absorbing fine particles is greater than a specific value, an infrared absorbing fine particle dispersion produced using the same and an infrared absorbing fine particle dispersion produced using the infrared absorbing fine particle dispersion also have excellent heat resistance.

However, when the crystal diameter value exceeds a certain value, it was concerned that the haze value due to Rayleigh scattering usually increases and the visibility of the infrared absorbing fine particle dispersion characterized by high visible light transparency decreases.

However, the inventors of the present invention have obtained the groundbreaking knowledge that, when the infrared absorbing fine particles are surface-treated infrared absorbing fine particles, it is not limited thereto, and it is possible to produce a low-haze infrared absorbing fine particle dispersion and an infrared absorbing substrate, thereby solving the above problem and leading to the present invention.

That is, the first invention for solving the above-described problem is,

The surface of infrared absorbing fine particles having a crystal diameter of 30 nm or more,

Surface-treated infrared absorbing fine particles characterized in that they are coated with a coating film comprising at least one selected from a hydrolysis product of a metal chelate compound, a polymer of a hydrolysis product of a metal chelate compound, a hydrolysis product of a metal cyclic oligomer compound, and a polymer of a hydrolysis product of a metal cyclic oligomer compound.

By using the surface-treated infrared absorbing fine particles of the present invention, it is possible to manufacture an infrared absorbing fine particle dispersion and an infrared absorbing substrate having high moisture resistance, heat resistance, and visible light transparency, excellent infrared absorption characteristics, and low haze.

Figure 1 is a schematic plan view of the crystal structure of a composite tungsten oxide having a hexagonal crystal structure.

The surface-treated infrared-absorbing fine particles according to the present invention are surface-treated infrared-absorbing fine particles, wherein the surface of the tungsten oxide fine particles or/and composite tungsten oxide fine particles, which are infrared-absorbing fine particles, is covered with a coating film including at least one selected from a hydrolysis product of a metal chelate compound, a polymer of a hydrolysis product of a metal chelate compound, a hydrolysis product of a metal cyclic oligomer compound, and a polymer of a hydrolysis product of a metal cyclic oligomer compound.

Hereinafter, the present invention will be described in detail in the following order: [1] infrared absorbing fine particles, [2] a surface treatment agent used for surface coating of infrared absorbing fine particles, [3] a method for surface coating of infrared absorbing fine particles, [4] an infrared absorbing fine particle dispersion and an infrared absorbing substrate obtained by using the surface-treated infrared absorbing fine particles, and an article.

In addition, in the present invention, "a coating film formed on the surface of the fine particles by using at least one selected from a hydrolysis product of a metal chelate compound, a polymer of a hydrolysis product of a metal chelate compound, a hydrolysis product of a metal cyclic oligomer compound, and a polymer of a hydrolysis product of a metal cyclic oligomer compound in order to impart moisture and heat resistance to the infrared absorbing fine particles" is sometimes simply described as a "coating film."

[1] Infrared absorbing particles

In general, it is known that materials containing free electrons exhibit reflection and absorption responses to electromagnetic waves around the region of sunlight with a wavelength of 200 nm to 2600 nm due to plasma vibration. It is known that when the powder of such a material is made into particles smaller than the wavelength of light, geometric scattering in the visible light region (wavelength of 380 nm to 780 nm) is reduced, thereby obtaining transparency in the visible light region.

In addition, in the present invention, “transparency” is used to mean “high transmittance with little scattering of light in the visible light range.”

In general, since there are no valid free electrons in tungsten oxide (WO ₃ ), it has poor absorption and reflection properties in the infrared region and is not effective as an infrared absorbing particle.

Meanwhile, WO ₃ having oxygen vacancies or composite tungsten oxides with positive elements such as Na added to WO ₃ are known to be conductive materials and materials having free electrons. And, through analysis of single crystals of materials having these free electrons, the response of free electrons to light in the infrared region has been suggested.

The present inventors have found that, in a specific part of the composition range of tungsten and oxygen, there is a particularly effective range as infrared absorbing particles, and have developed tungsten oxide particles and composite tungsten oxide particles which are transparent in the visible light range and absorbent in the infrared range.

Here, regarding the infrared absorbing fine particles of the present invention, tungsten oxide fine particles and/or composite tungsten oxide fine particles, the crystallite diameters of (1) tungsten oxide fine particles, (2) composite tungsten oxide fine particles, (3) tungsten oxide fine particles and composite tungsten oxide fine particles, and (4) tungsten oxide fine particles and composite tungsten oxide fine particles are described in this order.

(1) Tungsten oxide fine particles

The tungsten oxide fine particles according to the present invention are fine particles of tungsten oxide represented by the general formula WyOz (wherein W is tungsten, O is oxygen, and 2.2≤z/y≤2.999).

In tungsten oxide represented by the general formula WyOz, the composition range of tungsten and oxygen is preferably such that the composition ratio of oxygen to tungsten is less than 3, and further, when the infrared absorbing fine particles are represented by WyOz, 2.2≤z/y≤2.999.

When the value of z/y is 2.2 or more, the appearance of a WO ₂ crystal phase other than the intended one among the tungsten oxides can be avoided, and chemical stability as a material can be obtained, so that the particles become effective infrared absorbing particles. On the other hand, when the value of z/y is 2.999 or less, the required amount of free electrons are generated, so that the particles become effective infrared absorbing particles.

(2) Composite tungsten oxide microparticles

By adding the element M described later to the WO ₃ described above to form a composite tungsten oxide, free electrons are generated in the WO ₃ , and strong absorption characteristics derived from the free electrons are expressed particularly in the near-infrared region, making it effective as a near-infrared absorbing fine particle around 1000 nm.

That is, for the WO ₃ , more efficient infrared absorbing particles can be obtained by combining control of the oxygen amount and addition of the element M that generates free electrons. When the general formula of infrared absorbing particles obtained by combining control of the oxygen amount and addition of the element M that generates free electrons is expressed as MxWyOz (wherein M is the above-mentioned M element, W is tungsten, and O is oxygen), infrared absorbing particles that satisfy the relationships of 0.001≤x/y≤1 and 2.0≤z/y≤3 are preferable.

First, we explain the value of x/y, which represents the amount of element M added.

When the value of x/y is greater than 0.001, a sufficient amount of free electrons are generated in the composite tungsten oxide, so that the desired infrared absorption effect can be obtained. In addition, as the amount of element M added increases, the supply of free electrons increases and the infrared absorption efficiency also increases, but the effect is saturated when the value of x/y is approximately 1. In addition, when the value of x/y is less than 1, it is preferable because the generation of an impurity phase in the infrared absorbing fine particles can be avoided.

In addition, it is preferable that the element M is at least one selected from H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, I.

Here, from the viewpoint of stability in the MxWyOz to which the element M has been added, it is more preferable that the element M be at least one element selected from among an alkali metal, an alkaline earth metal, a rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, and Re. In addition, from the viewpoint of improving the optical properties and weather resistance as infrared absorbing fine particles, it is more preferable that the element M be an alkaline earth metal element, a transition metal element, a group 4B element, or a group 5B element.

Next, the value of z/y indicating the control of the oxygen amount will be described. Regarding the value of z/y, in the composite tungsten oxide represented by MxWyOz, in addition to the same mechanism as that of the tungsten oxide represented by WyOz described above, there is also a supply of free electrons by the amount of the element M added described above even when z/y = 3.0 or 2.0≤z/y≤2.2. Therefore, 2.0≤z/y≤3.0 is preferable, more preferably 2.2≤z/y≤3.0, and even more preferably 2.45≤z/y≤3.0.

In addition, when the composite tungsten oxide microparticles have a hexagonal crystal structure, the visible light region transmittance of the microparticles is improved, and the infrared region absorption is improved. This will be explained with reference to Fig. 1, which is a schematic plan view of the hexagonal crystal structure.

In Fig. 1, six octahedra formed by WO ₆ units, indicated by symbol 11, are assembled to form a hexagonal void, and within the void, an element M, indicated by symbol 12, is arranged to form one unit, and a plurality of these one units are assembled to form a hexagonal crystal structure.

And, in order to obtain the effect of improving the light transmittance in the visible light range and improving the light absorption in the infrared range, the composite tungsten oxide fine particles may contain the unit structure described using Fig. 1, and it does not matter whether the composite tungsten oxide fine particles are crystalline or amorphous.

When a cation of element M is added and present in the hexagonal pore, light transmittance in the visible light range is improved, and light absorption in the infrared range is improved. Here, in general, when an element M having a large ionic radius is added, the hexagonal crystal is easily formed. Specifically, when Cs, K, Rb, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn are added, the hexagonal crystal is easily formed. Of course, in elements other than these, as long as the above-described element M is present in the hexagonal pore formed by WO ₆ units, it is sufficient, and is not limited to the above-described elements.

When the composite tungsten oxide fine particles having a hexagonal crystal structure have a uniform crystal structure, the amount of the additive element M added is preferably 0.2 or more and 0.5 or less as the value of x/y, and more preferably 0.33. Since the value of x/y becomes 0.33, it is thought that the above-mentioned element M is arranged in all the hexagonal pores.

In addition, other than hexagonal, tetragonal and cubic complex tungsten oxides are also effective as infrared absorbing fine particles. The absorption position in the infrared region tends to change depending on the crystal structure, and the absorption position tends to move to the long wavelength side in the order of cubic < tetragonal < hexagonal. In addition, the order of hexagonal, tetragonal, and cubic crystals is that of less absorption in the visible light region. Therefore, for the purpose of transmitting more light in the visible light region and shielding more light in the infrared region, it is preferable to use hexagonal complex tungsten oxide. However, the tendency of the optical characteristics described here is only a rough tendency, and changes depending on the type of added element, the amount added, and the amount of oxygen, and the present invention is not limited thereto.

(3) Tungsten oxide microparticles and composite tungsten oxide microparticles

The infrared absorbing particles containing tungsten oxide particles or composite tungsten oxide particles according to the present invention largely absorb light in the near infrared range, particularly light having a wavelength of around 1000 nm, and therefore, the transmittance color tone is often from blue to green.

In addition, the dispersion particle size of tungsten oxide particles or composite tungsten oxide particles among the infrared absorbing particles can be selected depending on the intended use.

First, when used in applications where transparency is desired, it is desirable to have a particle size of 800 nm or less. This is because particles smaller than 800 nm do not completely block light by scattering, maintain visibility in the visible light range, and at the same time efficiently maintain transparency. In particular, when transparency in the visible light range is important, it is also desirable to consider scattering by particles.

When reducing scattering by these particles is important, the dispersed particle diameter is preferably 200 nm or less, and preferably 100 nm or less. The reason for this is that when the dispersed particle diameter of the particles is small, light scattering in the visible light range with a wavelength of 400 nm to 780 nm due to geometric scattering or Mie scattering is reduced, so that the infrared absorbing film becomes like milky glass, and clear transparency cannot be obtained. That is, when the dispersed particle diameter is 200 nm or less, the geometric scattering or Mie scattering is reduced, and the Rayleigh scattering region becomes. In the Rayleigh scattering region, scattered light is reduced in proportion to the sixth power of the particle diameter, so scattering is reduced as the dispersed particle diameter decreases, thereby improving transparency.

Also, when the dispersed particle size is 100 nm or less, scattered light is greatly reduced, which is desirable. From the viewpoint of avoiding light scattering, a smaller dispersed particle size is desirable, and industrial production is easy when the dispersed particle size is 1 nm or more.

By setting the above-mentioned dispersed particle diameter to 800 nm or less, the haze value of the infrared absorbing fine particle dispersion, in which the infrared absorbing fine particles according to the present invention are dispersed in a medium, can be set to have a visible light transmittance of 85% or less and a haze value of 30% or less. If the haze value is greater than 30%, it becomes like milky glass, and clear transparency cannot be obtained.

In addition, the dispersed particle size of infrared absorbing fine particles can be measured using ELS-8000 manufactured by Otsuka Electronics Co., Ltd., which is based on the dynamic light scattering method.

In addition, in tungsten oxide particles or composite tungsten oxide particles, the so-called "Magnelli phase" having a composition ratio expressed as 2.45≤z/y≤2.999 is chemically stable and has good absorption characteristics in the infrared region, and is therefore preferable as infrared absorbing particles.

(4) Crystal diameter of tungsten oxide microparticles and composite tungsten oxide microparticles

From the viewpoint of demonstrating excellent heat resistance and infrared absorption properties, the crystallite diameter of the infrared absorbing fine particles is preferably 30 nm or more. Furthermore, from the viewpoint of lowering the haze value in the infrared absorbing fine particle dispersion described later, the crystallite diameter of the infrared absorbing fine particles is preferably 30 nm or more and 100 nm or less, more preferably 30 nm or more and 70 nm or less, and most preferably 30 nm or more and 60 nm or less.

Therefore, regarding the crystallite diameter of the tungsten oxide fine particles or composite tungsten oxide fine particles according to the present invention, (i) a method for measuring the crystallite diameter, (ii) an effect of the crystallite diameter on heat resistance, (iii) an effect of the crystallite diameter on a haze value, and (iv) a method for producing the tungsten oxide fine particles and composite tungsten oxide fine particles are explained in this order.

(i) Method for measuring the diameter of the crystal

For the measurement of the crystallite diameter of tungsten oxide fine particles or composite tungsten oxide fine particles, measurement of an X-ray diffraction pattern by powder X-ray diffraction (θ-2θ method) and analysis by the Rietveld method are used. The measurement of an X-ray diffraction pattern can be performed using, for example, a powder X-ray diffraction device "X'Pert-PRO/MPD" manufactured by Spectris Co., Ltd., PANalytical.

(ii) Effect of crystal diameter on heat resistance

The effect of crystallite diameter of tungsten oxide microparticles and composite tungsten oxide microparticles on heat resistance is explained.

As described above, the infrared absorbing particles decompose and deteriorate on their surface due to heat exposure, and furthermore, the infrared absorption effect is lost. Factors of the decomposition and deterioration include oxygen and harmful radicals generated in the resin. At this time, if the crystallite diameter of the infrared absorbing particles is high, the specific surface area per unit mass of the infrared absorbing particles decreases. In other words, the surface decomposition and deterioration ratio of the infrared absorbing particles per unit mass decreases. As a result, it is thought that the crystallite diameter of the tungsten oxide particles and the composite tungsten oxide particles of 30 nm or more contributes to the improvement of heat resistance.

(iii) Effect of crystal diameter on haze value

The influence of the crystal diameter of tungsten oxide microparticles and composite tungsten oxide microparticles on the haze value of an infrared-absorbing microparticle dispersion in which the infrared-absorbing microparticles according to the present invention are dispersed in a medium is described.

As described in the section titled “(3) Tungsten oxide fine particles and composite tungsten oxide fine particles,” in the infrared-absorbing fine particle dispersion in which the infrared-absorbing fine particles according to the present invention are dispersed in a medium, when emphasis is placed on reducing scattering by the infrared-absorbing fine particles, the dispersed particle diameter is preferably 200 nm or less, and preferably 100 nm or less. From this viewpoint, the crystallite diameter of the tungsten oxide fine particles and the composite tungsten oxide fine particles is preferably 100 nm or less, and more preferably 70 nm or less.

(iv) Method for producing tungsten oxide microparticles and composite tungsten oxide microparticles

A method for producing tungsten oxide fine particles and composite tungsten oxide fine particles having a crystal diameter of 30 nm or more, preferably 30 nm or more and 100 nm or less, more preferably 30 nm or more and 70 nm or less, and most preferably 30 nm or more and 60 nm or less is not particularly limited, but an example thereof will be described.

First, prepare a tungsten oxide powder or a composite tungsten oxide powder having a crystallite diameter exceeding 100 nm (if it is a commercially available product, since the crystallite diameter of hexagonal cesium tungsten bronze (Cs _0.33 WO _z , 2.0 ≤ z ≤ 3.0) powder CWO (registered trademark) manufactured by Sumitomo Metal Mineral Industry Co., Ltd. exceeds 100 nm, this can be preferably used.) Then, while monitoring the crystallite diameter of the tungsten oxide powder or the composite tungsten oxide powder, a paint shaker or the like is used to perform pulverization and dispersion processing, and it is preferable to determine the pulverization and dispersion processing conditions and processing time that obtain infrared absorbing fine particles having a crystallite diameter in a preferable range of 30 nm or more, preferably 30 nm or more and 100 nm or less, more preferably 30 nm or more and 70 nm or less, and most preferably 30 nm or more and 60 nm or less.

[2] Surface treatment agent used for surface coating of infrared absorbing particles

The surface treatment agent used for surface coating of the infrared absorbing fine particles according to the present invention is at least one selected from a hydrolysis product of a metal chelate compound, a polymer of a hydrolysis product of a metal chelate compound, a hydrolysis product of a metal cyclic oligomer compound, and a polymer of a hydrolysis product of a metal cyclic oligomer compound.

And, from the viewpoint that the metal chelate compound or metal cyclic oligomer compound is preferably a metal alkoxide, a metal acetylacetonate or a metal carboxylate, it is preferable to have at least one selected from an ether bond, an ester bond, an alkoxy group or an acetyl group.

Here, the surface treatment agent according to the present invention is described in the following order: (1) metal chelate compound, (2) metal cyclic oligomer compound, (3) hydrolysis product and polymer of metal chelate compound or metal cyclic oligomer compound, and (4) amount of surface treatment agent added.

(1) Metal chelate compound

The metal chelate compound used in the present invention is preferably one or more kinds selected from Al-based, Zr-based, Ti-based, Si-based, and Zn-based chelate compounds containing an alkoxy group.

Examples of aluminum-based chelate compounds include aluminum alcoholates such as aluminum ethylate, aluminum isopropylate, aluminum sec-butyrate, and mono-sec-butoxyaluminum diisopropylate, or polymers thereof, ethyl acetoacetate aluminum diisopropylate, aluminum tris(ethyl acetoacetate), octylacetoacetate aluminum diisopropylate, stearyl acetoaluminum diisopropylate, aluminum monoacetylacetonate bis(ethyl acetoacetate), and aluminum tris(acetylacetonate).

These compounds are aluminum chelate compounds containing an alkoxy group obtained by dissolving aluminum alcoholate in an aprotic solvent, petroleum solvent, hydrocarbon solvent, ester solvent, ketone solvent, ether solvent, amide solvent, etc., adding β-diketone, β-ketoester, monohydric or polyhydric alcohol, fatty acid, etc. to this solution, heating and refluxing, and a substitution reaction of a ligand.

Examples of zirconia-based chelate compounds include zirconium alcoholates such as zirconium ethylate and zirconium butyrate, or polymers thereof, zirconium tributoxystearate, zirconium tetraacetylacetonate, zirconium tributoxy acetylacetonate, zirconium dibutoxy bis(acetylacetonate), zirconium tributoxyethyl acetoacetate, and zirconium butoxy acetylacetonate bis(ethyl acetoacetate).

Examples of titanium-based chelate compounds include titanium alcoholates such as methyl titanate, ethyl titanate, isopropyl titanate, butyl titanate, and 2-ethylhexyl titanate, and polymers thereof, titanium acetylacetonate, titanium tetraacetylacetonate, titanium octylene glycolate, titanium ethylacetoacetate, titanium lactate, and titanium triethanolaminate.

As a silicon-based chelate compound, a tetrafunctional silane compound represented by the general formula: Si(OR) ₄ (wherein R is a monovalent hydrocarbon group having 1 to 6 carbon atoms, which is the same or different) or a hydrolysis product thereof can be used. Specific examples of the tetrafunctional silane compound include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane. In addition, silane monomers (or oligomers) in which some or all of the alkoxy groups of these alkoxysilane monomers are hydrolyzed to become silanol (Si-OH) groups, and polymers that are self-condensed through a hydrolysis reaction are also applicable.

In addition, as hydrolysis products of tetrafunctional silane compounds (there is no appropriate term that designates all intermediates of tetrafunctional silane compounds), silane monomers in which some or all of the alkoxy groups are hydrolyzed to form silanol (Si-OH) groups, oligomers of four or five monomers, and polymers (silicone resins) having a weight average molecular weight (Mw) of about 800 to 8,000 can be mentioned. In addition, not all of the alkoxysilyl groups (Si-OR) in the alkoxysilane monomers are hydrolyzed to form silanol (Si-OH) during the course of the hydrolysis reaction.

As zinc-based chelate compounds, organic carboxylic acid zinc salts such as zinc octylate, zinc laurate, and zinc stearate, acetylacetone zinc chelate, benzoylacetone zinc chelate, dibenzoylmethane zinc chelate, and ethyl zinc acetoacetate chelate can be preferably exemplified.

(2) Metal ring oligomer compound

As the metal cyclic oligomer compound according to the present invention, it is preferable that it is at least one selected from Al-based, Zr-based, Ti-based, Si-based, and Zn-based cyclic oligomer compounds. Among these, a cyclic aluminum oligomer compound such as cyclic aluminum oxide octylate can be preferably exemplified.

(3) Hydrolysis products and polymers of metal chelate compounds or metal ring oligomer compounds

In the present invention, in the metal chelate compound or metal cyclic oligomer compound described above, a hydrolysis product in which all of the alkoxy groups, ether bonds, and ester bonds are hydrolyzed to form hydroxyl groups or carboxyl groups, a partial hydrolysis product in which a portion of the alkoxy groups, ether bonds, and ester bonds are hydrolyzed, and/or a polymer that self-condenses through the hydrolysis reaction is coated on the surface of the infrared-absorbing fine particles according to the present invention to form a coating film, thereby obtaining the surface-treated infrared-absorbing fine particles according to the present invention.

That is, the hydrolysis product in the present invention is a concept that includes a partial hydrolysis product.

However, in a reaction system involving an organic solvent such as alcohol, for example, even if water is present in the system in terms of stoichiometric composition, not all of the alkoxy groups, ether bonds, or ester bonds of the metal chelate compound or metal cyclic oligomer compound that are the starting materials are hydrolyzed, depending on the type or concentration of the organic solvent. Therefore, depending on the conditions of the surface coating method described below, there are cases where the molecule becomes an amorphous state with carbon C introduced into it even after hydrolysis.

As a result, the coating film may contain undissolved metal chelate compounds or/and metal ring oligomer compounds, but there is no particular problem if the amount is small.

(4) Amount of surface treatment agent added

The amount of the metal chelate compound or metal ring oligomer compound added is preferably 0.1 parts by mass or more and 1000 parts by mass or less in terms of the metal element, per 100 parts by mass of the infrared absorbing fine particles. More preferably, it is 1 part by mass or more and 500 parts by mass or less. Even more preferably, it is 10 parts by mass or more and 150 parts by mass or less.

When a metal chelate compound or a metal ring oligomer compound is present in an amount of 0.1 mass part or more, a hydrolysis product of these compounds or a polymer of the hydrolysis product has the effect of covering the surface of infrared absorbing fine particles, thereby obtaining the effect of improving moisture-heat resistance.

In addition, when the metal chelate compound or metal cyclic oligomer compound is 1000 parts by mass or less, it is possible to avoid excessive adsorption of infrared absorbing fine particles. In addition, since the improvement in moisture resistance due to surface coating is not saturated, an improvement in the coating effect can be expected.

In addition, since the amount of the metal chelate compound or the metal cyclic oligomer compound is 1000 parts by mass or less, the amount of adsorption for the infrared absorbing fine particles becomes excessive, and when the medium is removed, the fine particles can be easily assembled through a hydrolysis product of the metal chelate compound or the metal cyclic oligomer compound or a polymer of the hydrolysis product. By avoiding the undesired assembly of the fine particles, good transparency can be secured.

In addition, it is possible to avoid an increase in production costs due to an increase in the amount added and the processing time due to an excess of metal chelate compounds or metal cyclic oligomer compounds. Therefore, from an industrial perspective, it is preferable that the amount of metal chelate compounds or metal cyclic oligomer compounds added be 1000 parts by mass or less.

[3] Surface covering method

In the method for surface coating of infrared absorbing fine particles according to the present invention, first, a dispersion of infrared absorbing fine particles for forming a coating film (in the present invention, sometimes referred to as a “dispersion for forming a coating film”) is prepared by dispersing infrared absorbing fine particles in a suitable medium. Then, a surface treatment agent is added to the prepared dispersion for forming a coating film, and mixing and stirring are performed. Then, the surface of the infrared absorbing fine particles is coated with a coating film containing at least one selected from a hydrolysis product of a metal chelate compound, a polymer of a hydrolysis product of a metal chelate compound, a hydrolysis product of a metal cyclic oligomer compound, and a polymer of a hydrolysis product of a metal cyclic oligomer compound.

Here, the surface coating method according to the present invention is described in the following order: (1) preparation of a dispersion for forming a coating film, (2) preparation of a dispersion for forming a coating film using water as a medium, (3) preparation of a dispersion for forming a coating film by adjusting the amount of added water, and (4) treatment after mixing and stirring in the dispersion for forming a coating film.

(1) Preparation of dispersion for forming a coating film

In the dispersion liquid for forming a coating film according to the present invention, it is preferable to first finely pulverize infrared-absorbing fine particles, such as tungsten oxide or/and composite tungsten oxide, and disperse them in a suitable medium to keep them in a monodisperse state. In addition, it is important to ensure the dispersion state during this pulverization and dispersion treatment process and not to cause the fine particles to aggregate with each other. This is to avoid a situation in which, during the surface treatment process of the infrared-absorbing fine particles, the fine particles aggregate, the fine particles are surface-coated in the state of aggregates, and further, the aggregates remain in the infrared-absorbing fine particle dispersion described later, thereby reducing the transparency of the infrared-absorbing fine particle dispersion described later.

Therefore, by performing a pulverization and dispersion treatment on the dispersion liquid for forming a coating film according to the present invention, when the surface treatment agent according to the present invention is added, the hydrolysis product of the surface treatment agent and the polymer of the hydrolysis product can be uniformly and firmly coated on each infrared absorbing fine particle.

As a specific method for the pulverizing and dispersion treatment, for example, a pulverizing and dispersion treatment method using a device such as a bead mill, a ball mill, a sand mill, a paint shaker, or an ultrasonic homogenizer can be mentioned. Among these, pulverizing and dispersion treatment using a medium stirring mill such as a bead mill, a ball mill, a sand mill, or a paint shaker using a medium media such as beads, balls, or Ottawa sand is preferable because the time required to reach the desired dispersed particle size is short.

(2) Preparation of a dispersion for forming a coating film using water as a medium

The present inventors have found that, in the production of the above-described dispersion for forming a coating film, it is preferable to add a surface treatment agent according to the present invention while stirring and mixing the dispersion for forming a coating film using water as a medium, and further to immediately complete the hydrolysis reaction of the added metal chelate compound and metal cyclic oligomer compound. In the present invention, it is sometimes described as a "dispersion for forming a coating film using water as a medium."

It is thought that this is because the reaction order of the surface treatment agent of the present invention that has been added has an effect. That is, in a dispersion for forming a coating film using water as a medium, the hydrolysis reaction of the surface treatment agent always takes place first, and then the polymerization reaction of the generated hydrolysis product takes place. As a result, it is thought that this is because the amount of residual carbon C in the surface treatment agent molecules present in the coating film can be reduced compared to the case where water is not used as a medium. It is thought that by reducing the amount of residual carbon C in the surface treatment agent molecules present in the coating film, a high-density coating film can be formed.

In addition, among the dispersions for forming a coating film using the water as a medium described above, metal chelate compounds, metal ring oligomer compounds, hydrolysis products thereof, and polymers of the hydrolysis products may be decomposed into metal ions immediately after addition begins, but in such cases, the decomposition into the metal ions is completed when a saturated aqueous solution is formed.

Meanwhile, in the dispersion liquid for forming a coating film using the water as a medium, it is preferable that the dispersion concentration of the tungsten oxide or/and the composite tungsten oxide in the dispersion liquid for forming a coating film be 0.01 mass% or more and 80 mass% or less. When the dispersion concentration is in this range, the pH can be 8 or less, and the infrared absorbing fine particles according to the present invention maintain dispersion by electrostatic repulsion.

As a result, it is thought that the surfaces of all infrared absorbing fine particles are covered with a coating film including at least one selected from a hydrolysis product of a metal chelate compound, a polymer of a hydrolysis product of a metal chelate compound, a hydrolysis product of a metal cyclic oligomer compound, and a polymer of a hydrolysis product of a metal cyclic oligomer compound, and surface-treated infrared absorbing fine particles according to the present invention are produced.

(3) Preparation of dispersion for forming a coating film with adjusted amount of additives

As a modified example of the method for producing a coating film-forming dispersion using water as a medium described above, there is also a method of realizing the above-described reaction sequence by using an organic solvent as a medium for the coating film-forming dispersion and adjusting the amount of added water to an appropriate value. In the present invention, there are cases where it is described as "a coating film-forming dispersion using an organic solvent as a medium."

The manufacturing method is also convenient when it is desired to reduce the amount of moisture contained in the dispersion liquid for forming a coating film due to circumstances of a post-process.

Specifically, while stirring and mixing the dispersion liquid for forming a coating film using an organic solvent as a medium, the surface treatment agent according to the present invention and pure water are added dropwise in parallel. At this time, the medium temperature that affects the reaction speed and the dropping speed of the surface treatment agent and pure water are appropriately controlled. In addition, as the organic solvent, any solvent that dissolves in water at room temperature, such as alcohol, ketone, or glycol, may be used, and various solvents can be selected.

(4) Treatment after mixing and stirring in the dispersion for forming a coating film

The surface-treated infrared absorbing fine particles according to the present invention obtained in the manufacturing process of the dispersion for forming the above-described coating film can be used as a raw material for an infrared absorbing fine particle dispersion in a fine particle state, or in a state dispersed in a liquid medium or a solid medium.

In other words, the surface-treated infrared absorbing microparticles that have been generated do not require any further heat treatment to increase the density or chemical stability of the coating film. This is because the density and adhesion of the coating film are sufficiently high enough to obtain the desired moisture and heat resistance even without the heat treatment.

However, it is possible to heat-treat the dispersion for forming a coating film or the surface-treated infrared-absorbing fine particle powder for the purpose of obtaining a powder of surface-treated infrared-absorbing fine particles from the dispersion for forming a coating film, for the purpose of drying the obtained surface-treated infrared-absorbing fine particle powder, etc. However, in this case, care should be taken not to allow the heat-treating temperature to exceed the temperature at which the surface-treated infrared-absorbing fine particles strongly aggregate to form strong aggregates.

This is because, in most cases, transparency is required for the surface-treated infrared-absorbing fine particles according to the present invention, in the infrared-absorbing fine particle dispersion that is ultimately used, from their intended use. If an infrared-absorbing fine particle dispersion is produced using an aggregate as an infrared-absorbing material, a high haze value is obtained. If heat treatment is performed at a temperature exceeding the temperature at which strong aggregates are formed, in order to secure transparency of the infrared-absorbing fine particle dispersion, the strong aggregates are disintegrated and redispersed in a dry or/and wet manner. However, when disintegrating and redispersing, it is thought that the coating film on the surface of the surface-treated infrared-absorbing fine particles may be scratched, and in some cases, a portion of the coating film may be peeled off, exposing the surface of the fine particles.

As described above, the surface-treated infrared-absorbing fine particles according to the present invention do not require heat treatment after the treatment after mixing and stirring, and therefore do not cause strong agglomeration, and therefore dispersion treatment for breaking up the strong agglomeration is unnecessary or is completed in a short time. As a result, the coating film of the surface-treated infrared-absorbing fine particles according to the present invention is in a state where individual infrared-absorbing fine particles are covered without being scratched. In addition, it is thought that the infrared-absorbing fine particle dispersion manufactured using the surface-treated infrared-absorbing fine particles exhibits superior moisture-heat resistance than that obtained by a conventional method.

In addition, as described above, by reducing the residual amount of carbon C in the surface treatment agent molecules present in the coating film, a high-density coating film can be formed. From this viewpoint, in the surface-treated infrared-absorbing fine particle powder including the surface-treated infrared-absorbing fine particles, the contained carbon concentration is preferably 0.2 mass% or more and 5.0 mass% or less. More preferably, it is 0.5 mass% or more and 3.0 mass% or less.

[4] Infrared absorbing particle dispersion, infrared absorbing particle dispersion and infrared absorbing substrate obtained by using surface-treated infrared absorbing particles according to the present invention, and articles

Hereinafter, the infrared absorbing particle dispersion and the article obtained by using the surface-treated infrared absorbing particle according to the present invention are described in the following order: (1) infrared absorbing particle dispersion, (2) infrared absorbing particle dispersion, (3) infrared absorbing substrate, and (4) article using the infrared absorbing particle dispersion or infrared absorbing substrate.

(1) Infrared absorbing fine particle dispersion

The infrared absorbing fine particle dispersion according to the present invention is a liquid medium in which the surface-treated infrared absorbing fine particles according to the present invention are dispersed. As the liquid medium, one or more liquid media selected from an organic solvent, fat, a liquid plasticizer, a compound that is polymerized by curing, and water can be used.

The infrared absorbing fine particle dispersion according to the present invention is described in the following order: (i) manufacturing method, (ii) organic solvent used, (iii) fat used, (iv) liquid plasticizer used, (v) compound polymerized by curing used, (vi) dispersant used, and (vii) method of using the infrared absorbing fine particle dispersion.

(i) Manufacturing method

In order to produce the infrared-absorbing fine particle dispersion according to the present invention, the above-described coating film-forming dispersion is dried by heating or drying under conditions that can avoid strong agglomeration of the surface-treated infrared-absorbing fine particles, or by, for example, vacuum fluid drying, spray drying, or the like at room temperature, to obtain the surface-treated infrared-absorbing fine particle powder according to the present invention. Then, the surface-treated infrared-absorbing fine particle powder may be redispersed by adding it to the above-described liquid medium. In addition, it is also a preferable configuration to produce the infrared-absorbing fine particle dispersion by separating the coating film-forming dispersion into the surface-treated infrared-absorbing fine particles and the medium, and replacing the medium of the coating film-forming dispersion with the medium of the infrared-absorbing fine particle dispersion (so-called, solvent substitution).

In the treatment by vacuum fluid drying, since drying and disintegration are performed simultaneously under a reduced pressure atmosphere, the drying speed is fast and agglomeration of the surface-treated infrared-absorbing fine particles can be avoided. In addition, since drying is performed under a reduced pressure atmosphere, volatile components can be removed even at relatively low temperatures, so the amount of remaining volatile components can be made infinitely small. In addition, in the treatment by spray drying, secondary agglomeration due to the surface force of the volatile components is unlikely to occur, so even if a disintegration treatment is not performed, surface-treated infrared-absorbing fine particles that are relatively free of secondary agglomeration can be obtained.

Meanwhile, it is also a desirable configuration to match the medium of the dispersion liquid for forming a coating film and the medium of the infrared-absorbing fine particle dispersion liquid in advance, and to use the dispersion liquid for forming a coating film after surface treatment as an infrared-absorbing fine particle dispersion liquid as it is.

(ii) Organic solvent used

As the organic solvent used in the infrared absorbing fine particle dispersion of the present invention, alcohol-based, ketone-based, hydrocarbon-based, glycol-based, aqueous-based, etc. can be used.

Specifically, alcohol solvents such as methanol, ethanol, 1-propanol, isopropanol, butanol, pentanol, benzyl alcohol, diacetone alcohol, etc.;

Ketone solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone;

Ester solvents such as 3-methyl-methoxy-propionate;

Glycol derivatives such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol isopropyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol methyl ether acetate, and propylene glycol ethyl ether acetate;

Amides such as formamide, N-methylformamide, dimethylformamide, dimethylacetamide, and N-methyl-2-pyrrolidone;

Aromatic hydrocarbons such as toluene and xylene;

Ethylene chloride, chlorobenzene, etc. can be used.

And, among these organic solvents, in particular, dimethyl ketone, methyl ethyl ketone, methyl isobutyl ketone, toluene, propylene glycol monomethyl ether acetate, n-butyl acetate, etc. can be preferably used.

(iii) Maintenance in use

As the oil used in the infrared absorbing fine particle dispersion according to the present invention, vegetable oil or plant-derived oil is preferable.

As vegetable oils, drying oils such as linseed oil, sunflower oil, tung oil, and peanut oil can be used; semi-drying oils such as sesame oil, cottonseed oil, rapeseed oil, soybean oil, rice bran oil, and poppy oil can be used; and non-drying oils such as olive oil, coconut oil, palm oil, and dehydrated castor oil can be used.

As compounds derived from plant oils, fatty acid monoesters, ethers, etc., which are obtained by directly esterifying fatty acids and monoalcohols of plant oils, can be used.

Additionally, commercially available petroleum-based solvents can also be used as maintenance.

As commercially available petroleum solvents, Isopa (registered trademark) E, Exol (registered trademark) Hexane, Heptane, E, D30, D40, D60, D80, D95, D110, D130 (all manufactured by Exxon Mobil), etc. can be used.

(iv) Liquid plasticizer used

As the liquid plasticizer used in the infrared absorbing fine particle dispersion according to the present invention, for example, a plasticizer which is a compound of a monohydric alcohol and an organic acid ester, an ester-based plasticizer such as a polyhydric alcohol organic acid ester compound, a phosphoric acid-based plasticizer such as an organic phosphoric acid-based plasticizer, etc. can be used. In addition, it is preferable that all of them are liquid at room temperature.

Among these, a plasticizer which is an ester compound synthesized from a polyhydric alcohol and a fatty acid can be preferably used. The ester compound synthesized from the polyhydric alcohol and the fatty acid is not particularly limited, and for example, glycols such as triethylene glycol, tetraethylene glycol, and tripropylene glycol, and monobasic organic acids such as butyric acid, isobutyric acid, caproic acid, 2-ethylbutyric acid, heptyl acid, n-octyl acid, 2-ethylhexylic acid, pelargonic acid (n-nonylic acid), and decylic acid, obtained by the reaction thereof, and the like can be used.

In addition, tetraethylene glycol, tripropylene glycol, and ester compounds with the above-mentioned monobasic organic compounds may also be mentioned.

Among these, fatty acid esters of triethylene glycol such as triethylene glycol dihexanate, triethylene glycol di-2-ethylbutyrate, triethylene glycol di-octanate, and triethylene glycol di-2-ethylhexanonate can be used. In addition, fatty acid esters of triethylene glycol can also be preferably used.

(v) a compound polymerized by the curing agent used;

The compound that is polymerized by curing and used in the infrared absorbing fine particle dispersion according to the present invention is a monomer or oligomer that forms a polymer by polymerization or the like.

Specifically, methyl methacrylate monomer, acrylate monomer, styrene resin monomer, etc. can be used.

Above, the liquid media described can be used in combination of two or more. In addition, if necessary, acid or alkali can be added to these liquid media to adjust the pH.

(vi) Dispersant used

In order to further improve the dispersion stability of the surface-treated infrared absorbing particles in the infrared absorbing particle dispersion of the present invention and to avoid coarsening of the dispersed particle size due to re-agglomeration, it is also preferable to add various dispersants, surfactants, coupling agents, etc.

The dispersant, coupling agent, and surfactant may be selected according to the intended use, but those having an amine-containing group, a hydroxyl group, a carboxyl group, a sulfo group, or an epoxy group as a functional group are preferable. These functional groups have the effect of preventing aggregation and uniformly dispersing by adsorbing to the surface of the surface-treated infrared absorbing fine particles. A polymer-based dispersant having any of these functional groups in the molecule is more preferable.

In addition, an acrylic-styrene copolymer dispersant having a functional group can also be mentioned as a preferable dispersant. Among these, an acrylic-styrene copolymer dispersant having a carboxyl group as a functional group and an acrylic dispersant having an amine-containing group as a functional group can be mentioned as more preferable examples. The dispersant having an amine-containing group as a functional group preferably has a molecular weight Mw of 2,000 to 200,000 and an amine value of 5 to 100 mgKOH/g. In addition, in the dispersant having a carboxyl group, a molecular weight Mw of 2,000 to 200,000 and an acid value of 1 to 50 mgKOH/g are preferable.

Preferred specific examples of commercially available dispersants include SOLSPERSE (registered trademark) manufactured by Nippon Lubrizol Co., Ltd. (hereinafter the same applies) 3000, 5000, 9000, 11200, 12000, 13000, 13240, 13650, 13940, 16000, 17000, 18000, 20000, 21000, 24000SC, 24000GR, 26000, 27000, 28000, 31845, 32000, 32500, 32550, 32600, 33000, 33500, 34750, 35100, 35200, 36600, 37500, 38500, 39000, 41000, 41090, 53095, 55000, 56000, 71000, 76500, J180, J200, M387, etc.; SOLPLUS (registered trademark) (hereinafter the same) D510, D520, D530, D540, DP310, K500, L300, L400, R700, etc.; Big Chemistry Japan Saejae Disperbyk (registered trademark) (hereinafter the same) - 101, 102, 103, 106, 107, 108, 109, 110, 111, 112, 116, 130, 140, 142, 145, 154, 161, 162, 163, 164, 165, 166, 167, 168, 170, 171, 174, 180, 181, 182, 183, 184, 185, 190, 191, 192, 2000, 2001, 2009, 2020, 2025, 2050, 2070, 2095, 2096, 2150, 2151, 2152, 2155, 2163, 2164, Anti-Terra (registered trademark) (hereinafter the same)-U, 203, 204, etc.; BYK (registered trademark) (hereinafter the same) - P104, P104S, P105, P9050, P9051, P9060, P9065, P9080, 051, 052, 053, 054, 055, 057, 063, 065, 066N, 067A, 077, 088, 141, 220S, 300, 302, 306, 307, 310, 315, 320, 322, 323, 325, 330, 331, 333, 337, 340, 345, 346, 347, 348, 350, 354, 355, 358N, 361N, 370, 375, 377, 378, 380N, 381, 392, 410, 425, 430, 1752, 4510, 6919, 9076, 9077, W909, W935, W940, W961, W966, W969, W972, W980, W985, W995, W996, W9010, Dynwet800, Sic lean3700, UV3500, UV3510, UV3570, etc.; EFKA Additives EFKA (registered trademark) (hereinafter the same) 2020, 2025, 3030, 3031, 3236, 4008, 4009, 4010, 4015, 4020, 4046, 4047, 4050, 4055, 4060, 4080, 4300, 4310, 4320, 4330, 4340, 4400, 4401, 4402, 4403, 4500, 5066, 5220, 6220, 6225, 6230, 6700, 6780, 6782, 7462, 8503, etc.; BASF Japan Co., Ltd. JONCRYL (registered trademark) (hereinafter the same) 67, 678, 586, 611, 680, 682, 690, 819, -JDX5050, etc.; Otsuka Chemical Co., Ltd. TERPLUS (registered trademark) (hereinafter the same) MD1000, D1180, D1130, etc.; Ajinomoto Fine Techno Co., Ltd. AJISPER (registered trademark) (hereinafter the same) PB-711, PB-821, PB-822, etc. Dispalon (registered trademark) manufactured by Kusumoto Kasei Corporation (hereinafter the same applies) 1751N, 1831, 1850, 1860, 1934, DA-400N, DA-703-50, DA-325, DA-375, DA-550, DA-705, DA-725, DA-1401, DA-7301, DN-900, NS-5210, NVI-8514L, etc.; Examples thereof include Doa Kose Corporation's Alphon (registered trademark) (the same applies hereinafter) UH-2170, UC-3000, UC-3910, UC-3920, UF-5022, UG-4010, UG-4035, UG-4040, UG-4070, Rejeda (registered trademark) (the same applies hereinafter) GS-1015, GP-301, GP-301S, etc.; Mitsubishi Chemical Corporation's Dianal (registered trademark) (the same applies hereinafter) BR-50, BR-52, BR-60, BR-73, BR-77, BR80, BR-83, BR85, BR87, BR88, BR-90, BR-96, BR102, BR-113, BR116, etc.

(vii) Method of using infrared absorbing fine particle dispersion

The infrared absorbing particle dispersion of the present invention manufactured as described above can be applied to the surface of a suitable substrate and a dispersion film formed thereon to be used as an infrared absorbing substrate. That is, the dispersion film is a type of dried solidified product of the infrared absorbing particle dispersion.

In addition, the infrared-absorbing particle dispersion may be dried and pulverized to obtain a powdery infrared-absorbing particle dispersion according to the present invention (also sometimes referred to as “dispersion” in the present invention). That is, the dispersion is a type of dried solidified product of the infrared-absorbing particle dispersion. The dispersion is a powdery dispersion in which surface-treated infrared-absorbing particles are dispersed in a solid medium (such as a dispersant), and is distinct from the surface-treated infrared-absorbing particle powder described above. Since the dispersion contains a dispersant, it is possible to easily redisperse the surface-treated infrared-absorbing particles in the medium by mixing it with an appropriate medium.

The dispersion can be used as a raw material for adding surface-treated infrared absorbing particles in a dispersed state to an infrared absorbing product. That is, the dispersion in which the surface-treated infrared absorbing particles according to the present invention are dispersed in a solid medium can be dispersed again in a liquid medium and used as a dispersion liquid for an infrared absorbing product, or the dispersion can be used by kneading it into a resin as described below.

Meanwhile, an infrared absorbing particle dispersion solution prepared by mixing and dispersing the surface-treated infrared absorbing particles of the present invention in a liquid medium is used for various purposes utilizing photothermal conversion.

For example, by adding surface-treated infrared-absorbing fine particles to an uncured thermosetting resin, or by dispersing the surface-treated infrared-absorbing fine particles according to the present invention in a suitable solvent and then adding an uncured thermosetting resin, a curable ink composition can be obtained. The curable ink composition has excellent adhesion to the substrate when provided on a predetermined substrate and cured by irradiating it with infrared rays such as infrared. Then, in addition to its use as a conventional ink, the curable ink composition becomes a curable ink composition that is optimal for a stereolithography method for forming a three-dimensional object by applying a predetermined amount, irradiating it with electromagnetic waves such as infrared rays, curing it, and then stacking it.

(2) Infrared absorbing particulate dispersion

The infrared absorbing fine particle dispersion according to the present invention is one in which the surface-treated infrared absorbing fine particles according to the present invention are dispersed in a solid medium. In addition, as the solid medium, a solid medium such as resin or glass can be used.

The infrared absorbing fine particle dispersion of the present invention is described in the following order: (i) manufacturing method, (ii) moisture resistance, (iii) heat resistance, and (iv) haze value.

(i) Manufacturing method

When the surface-treated infrared absorbing fine particles of the present invention are mixed with a resin and formed into a film or board, it is possible to directly mix the surface-treated infrared absorbing fine particles with the resin. In addition, it is also possible to mix the infrared absorbing fine particle dispersion with the resin, or to add a powdery dispersion of the surface-treated infrared absorbing fine particles dispersed in a solid medium to a liquid medium and further to mix with the resin.

When a resin is used as a solid medium, it may be in the form of a film or board having a thickness of 0.1 ㎛ to 50 mm, for example.

In general, when the surface-treated infrared absorbing fine particles of the present invention are mixed into a resin, they are mixed by heating at a temperature near the melting point of the resin (around 200 to 300°C).

In this case, it is also possible to mix the surface-treated infrared-absorbing fine particles into a resin, pelletize them, and form a film or board using the pellets in each method. For example, it can be formed by an extrusion molding method, an inflation molding method, a solution casting method, a casting method, etc. The thickness of the film or board at this time can be appropriately set depending on the intended use, and the amount of filler for the resin (i.e., the blending amount of the surface-treated infrared-absorbing fine particles according to the present invention) varies depending on the thickness of the substrate or the required optical and mechanical properties, but is generally preferably 50 mass% or less with respect to the resin.

When the filler content in the resin is 50 mass% or less, the fine particles in the solid resin can be prevented from coagulating with each other, so that good transparency can be maintained. In addition, the amount of the surface-treated infrared absorbing fine particles according to the present invention can be controlled, so that it is advantageous in terms of cost.

Meanwhile, the infrared-absorbing fine particle dispersion, in which the surface-treated infrared-absorbing fine particles according to the present invention are dispersed in a solid medium, can also be used in a state in which it is further pulverized into a powder. When the above-mentioned configuration is adopted, in the powder-form infrared-absorbing fine particle dispersion, the surface-treated infrared-absorbing fine particles according to the present invention are already sufficiently dispersed in the solid medium. Therefore, by dissolving the powder-form infrared-absorbing fine particle dispersion in a so-called masterbatch, or mixing it with resin pellets or the like, it is possible to easily produce a liquid or solid infrared-absorbing fine particle dispersion.

In addition, the resin that becomes the matrix of the above-mentioned film or board is not particularly limited and can be selected according to the purpose. As a resin that is low cost, highly transparent, and widely versatile, PET resin, acrylic resin, polyamide resin, vinyl chloride resin, polycarbonate resin, olefin resin, epoxy resin, polyimide resin, etc. can be used. In addition, considering weather resistance, a fluorine resin can also be used.

(ii) Moisture resistance

The infrared absorbing fine particle dispersion of the present invention, when the dispersion, which has a visible light transmittance of about 80%, is exposed to a moist heat atmosphere at a temperature of 85°C and a relative humidity of 90% for 9 days, has an amount of change in the solar transmittance before and after the exposure of 2.0% or less and has excellent moisture-heat resistance.

(iii) Heat resistance

The infrared absorbing fine particle dispersion of the present invention has excellent heat resistance, and when the dispersion, which has a visible light transmittance of about 80%, is exposed to an air atmosphere at a temperature of 120°C for 30 days, the change in the solar transmittance before and after the exposure is 6.0% or less.

(iv) Haze value

The infrared absorbing fine particle dispersion of the present invention has a haze value of 1.5% or less at a visible light transmittance of about 80% and excellent visibility.

(3) Infrared absorbing material

The infrared absorbing substrate according to the present invention is formed as a coating layer with a dispersion film containing surface-treated infrared absorbing fine particles according to the present invention on at least one surface of one or more predetermined substrates.

By forming a dispersion film containing surface-treated infrared absorbing fine particles according to the present invention as a coating layer on a predetermined substrate surface, the infrared absorbing substrate according to the present invention has excellent moisture-heat resistance and chemical stability, and can be suitably used as an infrared absorbing material.

The infrared absorbing material according to the present invention is described in the following order: (i) manufacturing method, (ii) moisture resistance, (iii) heat resistance, and (iv) haze value.

(i) Manufacturing method

For example, by mixing the surface-treated infrared absorbing fine particles of the present invention, an organic solvent such as alcohol or a liquid medium such as water, a resin binder, and, if desired, a dispersant, an infrared absorbing fine particle dispersion is obtained. Then, after applying the obtained infrared absorbing fine particle dispersion to a suitable substrate surface, the liquid medium is removed or the resin binder is cured, whereby the infrared absorbing fine particle dispersion is directly laminated on the substrate surface to obtain an infrared absorbing substrate as a coating layer.

The above resin binder can be selected according to the intended use, and examples thereof include ultraviolet-curable resins, thermosetting resins, room-temperature curable resins, thermoplastic resins, etc. Meanwhile, an infrared-absorbing fine particle dispersion liquid that does not contain a resin binder may be laminated on the surface of a substrate, and after the lamination, a liquid medium containing a binder component may be applied onto the layer of the infrared-absorbing fine particle dispersion liquid.

Specifically, an infrared absorbing substrate may be exemplified in which a liquid infrared absorbing particle dispersion in which surface-treated infrared absorbing particles according to the present invention are dispersed in one or more liquid media selected from an organic solvent, an organic solvent in which a resin is dissolved, an organic solvent in which a resin is dispersed, and water is applied to the surface of a predetermined substrate, and the resulting coating film is solidified by an appropriate method. In addition, an infrared absorbing substrate may be exemplified in which a liquid infrared absorbing particle dispersion containing a resin binder is applied to the surface of a substrate, and the resulting coating film is solidified by an appropriate method. In addition, an infrared absorbing substrate may be exemplified in which a liquid infrared absorbing particle dispersion in which surface-treated infrared absorbing particles are dispersed in a powdery solid medium is mixed with a predetermined medium, and the resulting coating film is solidified by an appropriate method. Of course, an infrared absorbing substrate may also be exemplified in which an infrared absorbing particle dispersion in which two or more types of the various types of liquid infrared absorbing particle dispersions are mixed is applied to the surface of a predetermined substrate, and the resulting coating film is solidified by an appropriate method.

In addition, by adding a glass coating agent to the above-described infrared absorbing fine particle dispersion, wear resistance can be imparted to the infrared absorbing substrate according to the present invention.

As the glass coating agent to be contained, for example, a metal alkoxide or metal organic compound containing at least one of Sn, Ti, In, Si, Zr, and Al can be used. Among these, a compound containing Si is preferable, and it is preferable to use an organosilicon compound having an organic group bonded to a silicon atom, a silane coupling agent, a silane alkoxide, a polyorganosiloxane, a polysilazane, and an organic group having at least one reactive functional group. In addition, it is preferable that all of them are liquid at room temperature.

As polysilazanes, for example, perhydropolysilazanes, partially organopolysilazanes, and organosilazanes can be used.

As an organosilicon compound having an organic group bonded to a silicon atom and at least one of the organic groups having a reactive functional group, a compound including Si having an amino group, a mercapto group, an epoxy group, and a (meth)acryloyloxy group in the reactive group is preferable. For example, 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, 3-ureidpropyltriethoxysilane, N-(N-vinylbenzyl-2-aminoethyl)-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-Mercaptopropyltriethoxysilane, 3-Mercaptopropylmethyldimethoxysilane, 3-Mercaptopropylmethyldiethoxysilane, 3-Glycidoxypropyltrimethoxysilane, 3-Glycidoxypropylmethyldimethoxysilane, 3-Glycidoxypropyltriethoxysilane, 3-Isocyanatepropyltrimethoxysilane, 3-Isocyanatepropyltriethoxysilane, 3-Isocyanatepropyltriethoxysilane, 3-Isocyanatepropylmethyldimethoxysilane, 3-Isocyanatepropylmethyldiethoxysilane, etc. can be used.

In addition, when the glass coating agent is at least one selected from a silane coupling agent and a silane-based alkoxide, it is preferable that the liquid medium is at least one selected from aromatic hydrocarbons, ketones, ethers, alcohols, and water. In addition, when the glass coating agent is at least one selected from polysilazane and polyorganosilane, it is preferable that the liquid medium is at least one selected from aromatic hydrocarbons, ketones, and ethers.

Additionally, from the viewpoint of promoting hydrolysis of hydrolyzable silicon monomers and the like included in the glass coating agent, it is also a preferable configuration to add an acid to the infrared absorbing fine particle dispersion according to the present invention.

Examples of acids that can be used in the infrared absorbing fine particle dispersion according to the present invention include nitric acid, hydrochloric acid, sulfuric acid, trichloroacetic acid, trifluoroacetic acid, phosphoric acid, methanesulfonic acid, paratoluenesulfonic acid, and oxalic acid. Volatile acids are preferable because they volatilize upon heating and do not remain in the film after curing.

The acid acts as a catalyst that promotes the hydrolysis of a hydrolyzable silicon monomer and a partially hydrolyzed condensate of the silicon monomer. The content of the acid in the dispersion may be set without particular limitation within a range that can achieve the role of the catalyst, but is preferably set to about 0.001 to 0.1 mol/L in volume ratio with respect to the entire amount of the infrared absorbing fine particle dispersion.

The material of the above-described substrate is not particularly limited as long as it is transparent, but at least one selected from a glass substrate and a resin substrate is preferable. In addition, as the resin substrate, a resin board, a resin sheet, and a resin film are preferably used.

There are no special restrictions on the resin used in resin boards, resin sheets, and resin films, as long as it does not cause problems with the surface condition or durability of the required board, sheet, or film. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, polycarbonate polymers, acrylic polymers such as polymethyl methacrylate, styrene polymers such as polystyrene and acrylonitrile-styrene copolymers, olefin polymers such as polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, and ethylene-propylene copolymers, amide polymers such as vinyl chloride polymers and aromatic polyamides, imide polymers, sulfone polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, epoxy polymers, and various binary and ternary copolymers and graft copolymers thereof. Examples thereof include boards, sheets, and films containing transparent polymers such as blends. In particular, a polyester-based biaxially oriented film such as polyethylene terephthalate, polybutylene terephthalate, or polyethylene-2,6-naphthalate is suitable in terms of mechanical properties, optical properties, heat resistance, and economy. The polyester-based biaxially oriented film may be a copolymerized polyester.

(ii) Moisture resistance

In the above infrared absorbing material, when the infrared absorbing material is exposed to a moist heat atmosphere at a temperature of 85°C and a relative humidity of 90% for 9 days with a visible light transmittance of 80%, the change in solar transmittance before and after the exposure is 4.0% or less, and the material has excellent moisture-heat resistance.

(iii) Heat resistance

The infrared absorbing substrate of the present invention has excellent heat resistance, such that when the infrared absorbing substrate is exposed to an air atmosphere at a temperature of 120°C for 30 days with a visible light transmittance set to about 80%, the change in solar transmittance before and after the exposure is 2.0% or less.

(iv) Haze value

The infrared absorbing material according to the present invention has a haze value of 1.5% or less at a visible light transmittance of about 80% and excellent visibility.

(4) Articles using infrared absorbing fine particle dispersions or infrared absorbing materials

As described above, the infrared absorbing fine particle dispersion or the infrared absorbing material such as a film or board, which is an infrared absorbing substrate according to the present invention, has excellent moisture resistance, heat resistance, and chemical stability, and also has excellent visibility due to its low haze.

Therefore, these infrared absorbing articles can be suitably used as window materials for various buildings or vehicles, for example, for the purpose of sufficiently accepting visible light while blocking infrared light and maintaining brightness while suppressing temperature rise inside the room, and as filters used in PDPs (plasma display panels) for blocking infrared rays radiated forward from the PDP.

In addition, since the surface-treated infrared-absorbing fine particles according to the present invention have absorption in the infrared region, when an infrared laser is irradiated on a printing surface including the surface-treated infrared-absorbing fine particles, infrared rays having a specific wavelength are absorbed. Therefore, an anti-counterfeiting printed matter obtained by printing an anti-counterfeiting ink including the surface-treated infrared-absorbing fine particles on one side or both sides of a printing substrate can be determined to be genuine from the difference in the amount of reflection or transmission by irradiating infrared rays having a specific wavelength and reading the reflection or transmission thereof. The anti-counterfeiting printed matter is an example of the infrared-absorbing fine particle dispersion according to the present invention.

In addition, an ink can be prepared by mixing the infrared absorbing fine particle dispersion of the present invention and a binder component, applying the ink on a substrate, drying the applied ink, and then curing the dried ink to form a photothermal conversion layer. The photothermal conversion layer can generate heat only at a desired location with high positional precision by irradiation with an electromagnetic laser such as an infrared ray, and is applicable to a wide range of fields such as electronics, medicine, agriculture, and machinery. For example, it can be suitably used as a donor sheet used when forming an organic electroluminescent element by a laser transfer method, thermal paper for a thermal printer, or an ink ribbon for a thermal transfer printer. The photothermal conversion layer is an example of the infrared absorbing fine particle dispersion of the present invention.

In addition, by dispersing the surface-treated infrared-absorbing fine particles according to the present invention in a suitable medium and containing the dispersion on the surface and/or inside of a fiber, an infrared-absorbing fiber is obtained. By having the above-mentioned configuration, the infrared-absorbing fiber efficiently absorbs near-infrared rays, etc. from sunlight, etc., due to the inclusion of the surface-treated infrared-absorbing fine particles, and becomes an infrared-absorbing fiber with excellent heat retention, and at the same time, transmits light in the visible light range, so that it becomes an infrared-absorbing fiber with excellent design properties. As a result, it can be used for various purposes, such as textile products such as cold-weather clothing, sports clothing, stockings, and curtains that require heat retention, and other industrial textile products. The infrared-absorbing fiber is an example of the infrared-absorbing fine particle dispersion according to the present invention.

In addition, the film-shaped or board-shaped infrared absorbing fine particle dispersion according to the present invention can be applied as a material used for roofs or exterior walls of agricultural and horticultural houses. In addition, it can be used as an insulating material for agricultural and horticultural facilities by transmitting visible light to secure light necessary for photosynthesis of plants in agricultural and horticultural houses while efficiently absorbing light such as near-infrared light included in sunlight, thereby providing insulating properties. The insulating material for agricultural and horticultural facilities is an example of the infrared absorbing fine particle dispersion according to the present invention.

Example

Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to the following examples.

The dispersed particle size of the fine particles in the dispersions in the examples and comparative examples was expressed as an average value measured by a particle size measuring device (ELS-8000 manufactured by Otsuka Electronics Co., Ltd.) based on a dynamic light scattering method. In addition, the crystallite diameter was measured by a powder X-ray diffraction method (θ-2θ method) using a powder X-ray diffraction device (X'Pert-PRO/MPD manufactured by Spectris Co., Ltd. PANalytical), and calculated using the Rietveld method.

The optical properties of the infrared absorbing sheet and infrared absorbing substrate were measured using a spectrophotometer (U-4100 manufactured by Hitachi, Ltd.), and the visible light transmittance and solar radiation transmittance were calculated according to JISR3106.

The haze value of the infrared absorbing sheet and infrared absorbing substrate was measured using a haze meter (HM-150 manufactured by Murakami Shikisai Co., Ltd.) and calculated in accordance with JISK7105. When the haze value was 1.5% or less, it was judged that the haze was low and the visibility was good, and when the haze value exceeded 1.5%, it was judged that the haze value was high and the visibility was poor.

The method for evaluating the moisture resistance of an infrared absorbing sheet is as follows: the infrared absorbing sheet having a visible light transmittance of about 80% is exposed to a moist heat atmosphere at a temperature of 85°C and a relative humidity of 90% for 9 days. Then, for example, in the case of hexagonal cesium tungsten bronze, if the amount of change in the solar transmittance before and after the exposure is 2.0% or less, the moisture resistance is judged to be good, and if the amount of change exceeds 2.0%, the moisture resistance is judged to be insufficient.

The method for evaluating the heat resistance of an infrared absorbing sheet is to expose the infrared absorbing sheet having a visible light transmittance of about 80% to an air atmosphere at a temperature of 120°C for 30 days. Then, for example, in the case of hexagonal cesium tungsten bronze, if the change in the solar transmittance before and after the exposure is 6.0% or less, the heat resistance is judged to be good, and if the change exceeds 6.0%, the heat resistance is judged to be insufficient.

The method for evaluating the moisture resistance of an infrared absorbing material is as follows: the infrared absorbing material having a visible light transmittance of about 80% is exposed to a moist heat atmosphere at a temperature of 85°C and a relative humidity of 90% for 9 days. Then, for example, in the case of hexagonal cesium tungsten bronze, if the amount of change in the solar transmittance before and after the exposure is 4.0% or less, the moisture resistance is judged to be good, and if the amount of change exceeds 4.0%, the moisture resistance is judged to be insufficient.

The method for evaluating the heat resistance of an infrared absorbing material is to expose the infrared absorbing material having a visible light transmittance of about 80% to an air atmosphere at a temperature of 120°C for 30 days. Then, for example, in the case of hexagonal cesium tungsten bronze, if the change in solar transmittance before and after the exposure is 2.0% or less, the heat resistance is judged to be good, and if the change exceeds 2.0%, the heat resistance is judged to be insufficient.

In addition, the optical characteristic values (visible light transmittance, haze value) of the infrared absorption sheet mentioned here are values that include the optical characteristic values of the resin sheet as the substrate.

[Example 1]

A mixture of 25 mass% of hexagonal cesium tungsten bronze (Cs _0.33 WO _z , 2.0 ≤ z ≤ 3.0) powder CWO (registered trademark) (Y,M-01 manufactured by Sumitomo Metal Mineral Water Co., Ltd.) having a Cs/W (molar ratio) = 0.33 and 75 mass% of pure water was mixed, and the resulting mixture was loaded into a paint shaker containing 0.3 mmφZrO ₂ beads, and ground and dispersed for 4 hours to obtain a dispersion of Cs _0.33 WO _z fine particles according to Example 1. The dispersed particle size of the Cs _0.33 WO _z fine particles in the obtained dispersion was measured, and it was found to be 140 nm. In addition, as settings for the particle size measurement, the particle refractive index was set to 1.81, and the particle shape was non-spherical. In addition, the background was measured using pure water, and the solvent refractive index was set to 1.33. In addition, after removing the solvent of the obtained dispersion, the crystal diameter was measured and found to be 50 nm. The obtained dispersion of Cs _0.33 WO _z microparticles was mixed with pure water, and a dispersion A for forming a coating film according to Example 1 having a concentration of Cs _0.33 WO _z microparticles of 2 mass% was obtained.

Meanwhile, 2.5 mass% of aluminum ethyl acetoacetate diisopropylate as an aluminum-based chelate compound and 97.5 mass% of isopropyl alcohol (IPA) were mixed to obtain a surface treatment agent dilution solution a.

890 g of the obtained coating film-forming dispersion A was placed in a beaker, and while vigorously stirring with a stirrer equipped with a blade, 720 g of a surface treatment agent dilution solution a was added dropwise thereto over 6 hours. After the dropwise addition of the surface treatment agent dilution solution a, stirring was further performed at a temperature of 20°C for 24 hours, thereby producing a maturing solution according to Example 1. Next, the medium was evaporated from the maturing solution by vacuum fluidization drying, thereby obtaining a powder including the surface-treated infrared-absorbing fine particles according to Example 1 (surface-treated infrared-absorbing fine particle powder).

8 mass% of the surface-treated infrared-absorbing fine particle powder of Example 1, 24 mass% of a polyacrylate-based dispersant, and 68 mass% of toluene were mixed. The obtained mixture was loaded into a paint shaker containing 0.3 mmφZrO ₂ beads, and ground and dispersed for 1 hour to obtain an infrared-absorbing fine particle dispersion of Example 1. Next, the medium was evaporated from this infrared-absorbing fine particle dispersion by vacuum fluidization drying to obtain an infrared-absorbing fine particle dispersion of Example 1.

The infrared-absorbing fine particle dispersion and the polycarbonate resin according to Example 1 were dry blended so that the visible light transmittance of the infrared-absorbing sheet obtained thereafter was about 80% (in this example, the blend was made so that the concentration of the surface-treated infrared-absorbing fine particles was 0.06 mass%). The obtained blend was kneaded at 290°C using a twin-screw extruder, extruded through a T-die, and formed into a 0.75 mm thick sheet material by a calendar roll method, thereby obtaining the infrared-absorbing sheet according to Example 1. In addition, the infrared-absorbing sheet is an example of the infrared-absorbing fine particle dispersion according to the present invention.

The optical properties of the infrared absorbing sheet of Example 1 obtained were measured, and the visible light transmittance was 79.7%, the solar transmittance was 48.9%, and the haze value was 1.4%.

The infrared absorbing sheet of Example 1 thus obtained was exposed to a humid atmosphere at a temperature of 85°C and a relative humidity of 90% for 9 days, and the optical properties thereof were measured. The visible light transmittance was 80.3%, the solar transmittance was 49.8%, and the haze value was 1.4%. It can be seen that the change in visible light transmittance due to exposure to a humid atmosphere was 0.6%, and the change in solar transmittance was 0.9%, both of which were small, and that the haze value did not change.

In addition, the optical properties of the infrared absorbing sheet of Example 1 obtained were measured after exposing it to an air atmosphere at a temperature of 120°C for 30 days, and the visible light transmittance was 81.8%, the solar transmittance was 54.0%, and the haze value was 1.4%. It can be seen that the change in visible light transmittance due to exposure to a moist heat atmosphere was 2.1%, and the change in solar transmittance was 5.1%, both of which were small, and also that the haze value did not change.

The manufacturing conditions are shown in Table 1, and the evaluation results are shown in Table 3.

[Examples 2 and 3]

A mixture of 25 mass% of hexagonal cesium tungsten bronze (Cs _0.33 WO _z ) powder (Y,M-01 manufactured by Sumitomo Metal Mineral Water Co., Ltd.) having a Cs/W (molar ratio) of 0.33 and 75 mass% of pure water was mixed, and the resulting mixture was loaded into a paint shaker containing 0.3 mmφZrO ₂ beads, and subjected to pulverization and dispersion for 6 hours (Example 2) or 3 hours (Example 3) to obtain a dispersion of Cs _0.33 WO _z fine particles according to Examples 2 and 3.

The dispersion particle diameters of Cs _0.33 WO _z fine particles in the dispersions of Examples 2 and 3 were measured to be 120 nm and 160 nm, respectively. In addition, as settings for particle diameter measurement, the particle refractive index was set to 1.81, and the particle shape was set to non-spherical. In addition, the background was measured using pure water, and the solvent refractive index was set to 1.33.

In addition, after removing the solvent of the obtained dispersion, the crystallite diameters of the Cs _0.33 WO _z microparticles of Examples 2 and 3 were measured, and were 42 nm and 60 nm, respectively.

The dispersions of Cs _0.33 WO _z fine particles according to Examples 2 and 3 were mixed with pure water to obtain a coating film-forming dispersion B according to Example 2 having a concentration of 2 mass% of Cs _0.33 WO _z fine particles and a coating film-forming dispersion C according to Example 3.

By performing the same operation as Example 1, except that instead of the coating film-forming dispersion A, coating film-forming dispersions B and C were used, surface-treated infrared-absorbing fine particle powder, infrared-absorbing fine particle dispersion, infrared-absorbing fine particle dispersion powder, and infrared-absorbing sheet according to Examples 2 and 3 were obtained, and the same evaluation as Example 1 was performed. The manufacturing conditions are shown in Table 1, and the evaluation results are shown in Table 3.

[Comparative Example 1]

7 mass% of hexagonal cesium tungsten bronze powder, 24 mass% of a polyacrylate-based dispersant, and 69 mass% of toluene were mixed, and the obtained mixture was charged into a paint shaker containing 0.3 mmφZrO ₂ beads, and ground and dispersed for 4 hours to obtain a dispersion D for forming a coating film according to Comparative Example 1. The dispersed particle diameter of infrared absorbing fine particles in the obtained dispersion D for forming a coating film was measured to be 100 nm. In addition, as settings for the particle diameter measurement, the particle refractive index was set to 1.81, and the particle shape was non-spherical. In addition, the background was measured using toluene, and the solvent refractive index was set to 1.50. In addition, after the solvent of the obtained dispersion was removed, the crystallite diameter was measured to be 32 nm.

Next, the surface treatment agent was not added to the dispersion D for forming the coating film, and the infrared-absorbing fine particle dispersion according to Comparative Example 1 was prepared as is. The medium was evaporated from the infrared-absorbing fine particle dispersion according to Comparative Example 1 by vacuum fluidization drying, thereby obtaining the infrared-absorbing fine particle dispersion according to Comparative Example 1.

The infrared absorbing particle dispersion and polycarbonate resin for Comparative Example 1 were dry blended so that the concentration of the infrared absorbing particles became 0.075 mass%. The obtained blend was kneaded at 290°C using a twin-screw extruder, extruded through a T-die, and formed into a 0.75 mm thick sheet material by a calendar roll method, thereby obtaining an infrared absorbing sheet for Comparative Example 1.

The optical properties of the infrared absorption sheet of Comparative Example 1 were measured, and the visible light transmittance was 79.2%, the solar transmittance was 48.4%, and the haze value was 1.0%.

The infrared absorbing sheet of Comparative Example 1 was exposed to a humid atmosphere of 85℃ and 90% relative humidity for 9 days, and the optical properties were measured. The visible light transmittance was 81.2%, the solar transmittance was 52.6%, and the haze value was 1.2%. The change in visible light transmittance due to exposure to a humid atmosphere was 2.0%, and the change in solar transmittance was 4.2%, which can be seen to be greater than in the examples. In addition, the change in haze value was 0.2%.

In addition, the infrared absorbing sheet of Comparative Example 1 obtained was exposed to an air atmosphere at a temperature of 120℃ for 30 days, and the optical properties were measured. The visible light transmittance was 83.3%, the solar transmittance was 59.8%, and the haze value was 1.6%. The change in visible light transmittance due to exposure to a moist heat atmosphere was 4.1%, and the change in solar transmittance was 11.4%, which can be seen to be greater than in the example. In addition, the change in haze value was 0.6%.

The manufacturing conditions are shown in Table 2, and the evaluation results are shown in Table 4.

[Comparative Example 2]

A surface treatment agent was not added to the dispersion A for forming a coating film according to Example 1, and the dispersion was made into an infrared fine particle dispersion according to Comparative Example 2 as is. The medium was evaporated from the infrared-absorbing fine particle dispersion according to Comparative Example 2 by vacuum fluid drying, thereby obtaining an infrared-absorbing fine particle dispersion according to Comparative Example 2.

Except that the surface-treated infrared-absorbing fine particle powder of Comparative Example 2 was used instead of the surface-treated infrared-absorbing fine particle powder of Comparative Example 1, the same operation as Comparative Example 1 was performed to obtain an infrared-absorbing fine particle dispersion, an infrared-absorbing fine particle dispersion, and an infrared-absorbing sheet of Comparative Example 2, and the same evaluation as Example 1 was performed. The manufacturing conditions are shown in Table 2, and the evaluation results are shown in Table 4.

[Comparative Example 3]

A mixture of 25 mass% of hexagonal cesium tungsten bronze (Cs _0.33 WO _z ) powder (Y,M-01 manufactured by Sumitomo Metal Mineral Industry Co., Ltd.) having a Cs/W (molar ratio) of 0.33 and 75 mass% of pure water was mixed, and the resulting mixture was loaded into a paint shaker containing 0.3 mmφZrO ₂ beads and subjected to pulverization and dispersion for 10 hours to obtain a dispersion of Cs _0.33 WO _z fine particles according to Comparative Example 3.

The dispersion particle size of Cs _0.33 WO _z fine particles in the dispersion solution of Comparative Example 3 obtained was measured to be 100 nm. In addition, as the settings for particle size measurement, the particle refractive index was set to 1.81, and the particle shape was set to non-spherical. In addition, the background was measured using pure water, and the solvent refractive index was set to 1.33.

In addition, after removing the solvent of the obtained dispersion, the crystallite diameter of the Cs _0.33 WO _z microparticles of Comparative Example 3 was measured and found to be 32 nm.

The dispersion of Cs _0.33 WO _z fine particles for Comparative Example 3 was mixed with pure water, and a dispersion E for forming a coating film for Comparative Example 3 having a concentration of Cs _0.33 WO _z fine particles of 2 mass% was obtained.

By performing the same operation as in Example 1, except that the dispersion E for forming a coating film was used instead of the dispersion A for forming a coating film, a surface-treated infrared-absorbing fine particle powder, an infrared-absorbing fine particle dispersion, an infrared-absorbing fine particle dispersion, and an infrared-absorbing sheet for Comparative Example 3 were obtained, and the same evaluation as in Example 1 was performed. The manufacturing conditions are shown in Table 2, and the evaluation results are shown in Table 4.

[Example 4]

10 g of the surface-treated infrared-absorbing fine particle powder of Example 1 was mixed with 23 g of isopropyl alcohol, 16 g of tetraethoxysilane, and 10 g of 3-glycidoxypropyltrimethoxysilane to obtain a mixture. The obtained mixture was loaded into a paint shaker containing 0.3 mmφZrO ₂ beads, and ground and dispersed for 1 hour. Thereafter, 40 g of 0.1 mol/liter nitric acid was added, and the mixture was stirred at a temperature of 20°C for 1 hour to obtain an infrared-absorbing fine particle dispersion of Example 4.

Additionally, tetramethoxysilane and 3-glycidoxypropyltrimethoxysilane are glass coating agents of silane alkoxides.

The infrared absorbing fine particle dispersion according to Example 4 was applied onto a glass substrate having a thickness of 3 mm using a bar coater (IMC-700 manufactured by Imoto Seisakusho) to form a coating film. The coating film was heated at 150°C for 30 minutes to form a coating layer, thereby obtaining an infrared absorbing substrate according to Example 4. In addition, the film thickness of the coating layer was measured and found to be 3 μm.

The optical properties of the infrared absorbing substrate for Example 4 were measured, and the visible light transmittance was 79.5%, the solar radiation transmittance was 46.7%, and the haze was 0.7%.

The infrared absorbing substrate of Example 4 thus obtained was exposed to a humid atmosphere at a temperature of 85°C and a relative humidity of 90% for 9 days, and the optical properties were measured to show that the visible light transmittance was 81.6%, the solar transmittance was 50.0%, and the haze was 0.7%. The change in the visible light transmittance due to exposure to the humid atmosphere was 2.1%, and the change in the solar transmittance was 3.3%, both of which were small, and the haze did not change.

In addition, the optical properties of the infrared absorbing substrate of Example 4 obtained were measured after exposing it to an air atmosphere at a temperature of 120°C for 30 days, and the visible light transmittance was 80.7%, the solar transmittance was 48.3%, and the haze value was 0.7%. The change in visible light transmittance due to exposure to a moist heat atmosphere was 1.2%, and the change in solar transmittance was 1.6%, both of which were small, and the haze did not change.

The manufacturing conditions are shown in Table 5, and the evaluation results are shown in Table 6.

[Comparative Example 4]

By performing the same operation as in Example 4, except that the surface-treated infrared-absorbing fine particle powder of Comparative Example 3 was used instead of the surface-treated infrared-absorbing fine particle powder of Example 4, an infrared-absorbing fine particle dispersion and an infrared-absorbing base material of Comparative Example 4 were obtained, and the same evaluation as in Example 4 was performed. The manufacturing conditions are shown in Table 5, and the evaluation results are shown in Table 6.

[Comparative Example 5]

Except that the infrared-absorbing fine particle dispersion of Comparative Example 2 was used instead of the surface-treated infrared-absorbing fine particle powder of Comparative Example 4, the same operation as Comparative Example 4 was performed to obtain an infrared-absorbing fine particle dispersion and an infrared-absorbing base material of Comparative Example 5, and the same evaluation as Example 4 was performed. The manufacturing conditions are shown in Table 5, and the evaluation results are shown in Table 6.

From the above results, it was confirmed that the infrared absorbing sheets according to Examples 1 to 3 and the infrared absorbing substrate according to Example 4 had excellent visibility and excellent moisture and heat resistance because they had low haze.

Meanwhile, it was confirmed that the infrared absorbing sheets of Comparative Examples 1 to 3 and the infrared absorbing substrates of Comparative Examples 4 and 5 did not satisfy any of the requirements of visibility, moisture resistance, and heat resistance, and did not satisfy the needs of the market.

Claims (14)

The surface of infrared absorbing fine particles having a crystal diameter of 42 nm or more,
Comprising surface-treated infrared absorbing fine particles coated with a coating film comprising at least one selected from a hydrolysis product of a metal chelate compound, a polymer of a hydrolysis product of a metal chelate compound, a hydrolysis product of a metal cyclic oligomer compound, and a polymer of a hydrolysis product of a metal cyclic oligomer compound,
The above infrared absorbing fine particles are expressed by a general formula WyOz (wherein W is tungsten, O is oxygen, 2.2≤z/y≤2.999), or/and a general formula MxWyOz (wherein M is at least one element selected from H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, I, Yb, W is tungsten, O is oxygen, 0.001≤x/y≤1, 2.0≤z/y≤3.0),
A surface-treated infrared absorbing fine particle powder, characterized in that the metal chelate compound or the metal ring oligomer compound contains one or more metal elements selected from Al, Zr, Ti, Si, and Zn. A surface-treated infrared absorbing fine particle powder characterized in that the crystal diameter in claim 1 is 42 nm or more and 60 nm or less. A surface-treated infrared absorbing fine particle powder, characterized in that in claim 1, the metal chelate compound or the metal cyclic oligomer compound has at least one selected from an ether bond, an ester bond, an alkoxy group, and an acetyl group. An infrared absorbing particle dispersion, characterized in that the surface-treated infrared absorbing particle powder described in any one of claims 1 to 3 is dispersed in a predetermined liquid medium, and the liquid medium is at least one liquid medium selected from an organic solvent, fat, a liquid plasticizer, a compound that is polymerized by curing, and water. An infrared absorbing particle dispersion, characterized in that the surface-treated infrared absorbing fine particle powder described in any one of claims 1 to 3 is dispersed in a predetermined solid resin, and the solid resin is at least one resin selected from a fluororesin, a PET resin, an acrylic resin, a polyamide resin, a vinyl chloride resin, a polycarbonate resin, an olefin resin, an epoxy resin, and a polyimide resin. An infrared absorbing particle dispersion characterized by being a dry solidified product of the infrared absorbing particle dispersion described in claim 4. An infrared absorbing substrate having a coating layer on at least one side of one or more substrates,
An infrared absorbing substrate, characterized in that the coating layer comprises the surface-treated infrared absorbing fine particle powder described in any one of claims 1 to 3. An infrared absorbing substrate, characterized in that in claim 7, the coating layer further contains a glass coating agent. An infrared absorbing material, characterized in that in claim 8, the glass coating agent is at least one selected from a silane coupling agent, a silane-based alkoxide, a polysilazane, and a polyorganosilane. An infrared absorbing substrate, characterized in that in claim 7, the substrate is at least one type selected from a glass substrate and a resin substrate. delete delete delete delete

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